This invention relates generally to polychlorinated biphenyls, and more particularly, relates to reagents and an immunoassay for detecting the presence or amount of polychlorinated biphenyls in a test sample.
Current Environmental Protection Agency (EPA) approved methodology (EPA method 608, SW 846 method 8080) for determining the presence or amount of polychlorinated biphenyls (PCBs) in a test sample involves extracting the sample with an organic solvent such as hexane or methylene chloride, and then using a gas chromatograph (GC) equipped with an electron capture detector (ECD) to analyze the extract. A more rigorous pretreatment of test sample involving washing with sulfuric acid, mercury desulfurization, or purification on magnesium silicate (Florosil.RTM., available from Aldrich Chem. Co., Milwaukee, WI) or alumina sometimes is required. The problems encountered with this methodology are inherent to the analytical technique: the procedure is time-consuming and expensive since the GC/ECD runs only one sample at a time, requires 40-60 minutes per test sample, and highly trained technical personnel are required to perform the testing and maintain the equipment.
Various radioimmunoassays (RIAs) for detecting PCBs have been reported. For example, a radioimmunoassay for detecting the commercial PCB mixtures aroclor 1242,1248 and 1254 has been reported in M. I. Luster, et al., Toxicology and Applied Pharmacology, 1979, 50, 147-155. In this method, antisera raised in rabbits using three immunogens, haptens 4-amino-4'-chlorobiphenyl, 2-amino-4,5,3',4'-tetrachlorobiphenyl, and 3-amino-2,6,2',6'-tetrachlorobiphenyl were linked via an adipamide linker arm to bovine serum albumin (BSA) and thyroglobulin, and .sup.125 I tracers used in the method were prepared from the 5-bromovaleramide derivatives of the haptens. Minimum sensitivity of 1-3 ng was reported on standard samples. Feasibility was shown for detecting mixtures of these aroclors in mineral oil.
The detection of PCBs in milk and blood by radioimmunoassay is reported in W. H. Newsome and J. B. Shields, Intern. J. Environ, Anal. Chem., 1981, 10, 295-304. The hapten employed in this assay was 2-amino-2',4,4',5,5'-pentachlorobiphenyl. Antisera was raised in rabbits using a succinamide linking arm to the hapten and the radiotracer was 2-[.sup.125 iodo]-2',4,4',5,5'-pentachlorobiphenyl. The minimum sensitivity reported was 0.1 ng for aroclor 1260. The sensitivity reported for aroclor 1254 was similar, but lower aroclors were not detected with the same sensitivity.
U.S. Pat. No. 4,456,691 to S. Stark teaches the preparation of polyclonal antibodies ot PCBs using aroclor 1254 which has been aminated, diazotized and coupled to Bovine Serum Albumin (BSA). The antisera was evaluated by an RIA.
Radioimmunoassays are known to provide sensitive results. However, these assays usually require a higher degree of technical expertise, are more cumbersome that other immunoassay methods, require expensive equipment and involve the handling of radioactive materials.
It would be advantageous to provide an assay which could be used to detect aroclors 1221, 1232, 1242, 1016, 1248, 1254 and 1260 in single assay. It also would be advantageous to provide an assay which did not employ the use of radioisotopes. It further would be advantageous to provide an assay which utilizes a similar sample preparation to that of the EPA method, but can detect the presence or amount of PCBs in the test sample more rapidly and in an automated system.